Cutting apparatuses including a circular blade (disk cutter) for cutting objects and sanders for grinding a surface of an object such as concrete blocks are known. Japanese Laid-open patent application publication No. 2000-210866 discloses such a sander (see pages 1 to 2, FIGS. 1–2). This conventional sander is used in such a manner that one side of rotating cutting edges of a circular blade is pressed on the surface of the object. The sander mainly includes a body having a driving power source for a circular blade (disc cutter), a cutting unit, mounted on the body, having the circular blade, a dust cover (chip guard) for covering the circular blade, and a dust discharging unit (chip discharging unit) attached to the cutting unit for sucking chips (dust) in the dust cover and externally discharging the dust.
More specifically, in this prior art, the dust cover is fixed to a lower part of the body with screws or the like, and an output shaft of a drive power source protrudes into the dust cover to provide a mounting structure for detachably mounting the circular blade on output shaft within the dust cover. The dust cover is at an opening edge thereof provided with a brush. When edges of the circular blade are pressed to the surface of an object, the brush closes an open space between the surface of the object and the brush. This prevents chips (dust) from being scattered. Thus, the chips are discharged to a predetermined dust collecting bag (filter) by the dust discharging unit without scattering.
However, in the structure of the sander disclosed in Japanese Laid-open patent application publication No. 2000-210866, because the pulley and the flat belt is exposed to the inside of the dust cover, there is a problem that the fine chips (powder dust) within the dust cover may stick to these members, which can cause slippage therebetween.
Further, since the bodies and the circular blades are general members, there are various types of products having various configurations on market. On the other hand, due to a lack of compatibility, the dust cover is typically specially designed for each type of the sander.
In the dust cover disclosed in Japanese Laid-open patent application publication No. 2000-210866, there is a problem that the heights of the dust covers from the body to the edge portion are the same, so that there is no compatibility with other circular blades (disk cutters) having different sizes.